Gigavps recently came in the #CGMiner channel to report a bug about the "semi-graphical" command line display malfunctioning with more than 16 devices - he had just turned on a total of 17+ FPGAs.
How did I confirm this bug? Not with 17 FPGAs - can't expect every developer to have that kind of equipment handy for testing - but by using CPUmining to generate 17 CPU threads. So yet another thing CPUmining helps test is CGMiner's basic frameworks themselves.
Unfortunately, ckolivas expressed that he would refuse to merge a fix for this issue even if I wrote it. Pretty much defeats the point. (Though I did still offer to debug and write the fix for Gigavps, at a reasonable per-hour cost; I can't blame him for declining, considering it wouldn't get merged)
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ckolivas' commit to resolve that 4 days ago that gigavps is using ...
Disable per-device status lines when there are more than 8 devices since screen output will be corrupted, enumerating them to the log output instead at startup
https://github.com/ckolivas/cgminer/commit/f3e4305620825dbaa61eb26b2a0b6d9f5c924338
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How about 17 GPU threads ...
LOL I tried 10 threads per GPU on my 2x6950 rig and rather oddly the MH/s went up by 10MH/s each GPU for the first few minutes and then settled back down to the same value after that as with 2 threads per GPU